score = int(input('请输入成绩：'))
if 90 <= score <= 100:
    print('优')
elif 80 <= score < 90:
    print('良')
elif 70 <= score < 80:
    print('中')
elif 60 <= score < 70:
    print('及格')
elif 0 <= score < 60:
    print('不及格')
else:  # 输入>100或<0的分数时报错
    print("错误")
print('计科1814-39-易芳')
